1. Field
The present invention relates generally to communication systems, and more specifically to frame receipt negative acknowledgements in such systems.
2. Background
Data Services for third-generation (3G) systems, including both code-division multiple access 2000 (cdma2000) and wideband code-division multiple access (WCDMA), were designed around a physical layer framework that was optimized for voice transport. While 3G systems are designed to handle both services, voice services in particular are characterized by symmetric traffic loading (between the forward link and the reverse link) and guaranteed quality of service (for parameters such as latency, delay, etc.). Packet data services, however, are characterized by possibly asymmetric traffic loading that involves short messages (e.g., requests for data) of low bandwidth demand and very long messages (e.g., data downloads) of high bandwidth demand. There are some types of data traffic that are bursty, not all are (e.g., video).
To increase the likelihood that a frame will be successfully transmitted during a data transmission a system may employ a Radio Link Protocol (RLP) to track the frames transmitted successfully, and to perform frame retransmission when a frame is not transmitted successfully. Retransmission is performed up to a predetermined number of times, and it is the responsibility of the higher layer protocols to take additional steps to ensure that the frame is successfully transmitted. If the system sends the packets in an out-of-order sequence, the receiver is not readily able to distinguish if the packet is lossed or will be received at a later time. Such determination and waiting incurs processing time at the receiver, latency between the transmitter and receiver, as well as additional storage capacity at both the receiver and transmitter. Some systems incur a specific delay period that may prolong each communication.
There is therefore a need for a modified technique to more efficiently detect if a frame is lost so that a negative acknowledge message may be transmitted.